课后作业1

1.编写一个程序，指定一个文件夹，能自动计算出其总容量

package test;
import java.io.File;
import java.util.ArrayList;
 
public class test1 {
   static long size=0;
 private static ArrayList<String> filelist=new ArrayList<String>();
 public static void main(String[] args) {
  test1 s=new test1();
  String filePath="D:\\abc";
  s.getFiles(filePath);
  
 }
 
 void getFiles(String filePath) {
  
  File root=new File(filePath);
  File[] files=root.listFiles();
  for(File file:files) {
   if(file.isDirectory()) {
    getFiles(file.getAbsolutePath());
    filelist.add(file.getAbsolutePath());
    
   }
   else {
    size+=file.getAbsolutePath().length();
   }
  }
  System.out.println(size);
 
  
 }
   
}

　　

2.编写一个文件加解密程序，通过命令行完成加解密工作

 

package test;


import java.io.*;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class test2 {
    public static void encryption() throws IOException {
        BufferedInputStream sc = new BufferedInputStream(new FileInputStream("D:\\abc\\1.txt"));
        BufferedOutputStream scan = new BufferedOutputStream(new FileOutputStream("D:\\abc\\2.txt"));       
        int b;
        while((b = sc.read()) != -1) {
            scan.write(b ^ 123);
        }   
        sc.close();
        scan.close();
    }
    public static void main(String[] args) throws IOException {
        encryption();
    }
}

　　

3.编写一个文件分割工具，能把一个大文件分割成多个小的文件。并且能再次把它们合并起来得到完整的文件。

package test;
import java.io.*;
public class test3 {
	public static void main(String args[])
	{        try {            
		FileReader read = new FileReader("D:\\abc\\1.txt");            
		BufferedReader br = new BufferedReader(read);            
		String row;             
		int rownum = 1;            
		int fileNo = 1;            
		FileWriter fw = new FileWriter("D:/text"+fileNo +".txt");            
		while ((row = br.readLine()) != null) {                
			rownum ++;                fw.append(row + "\r\n");           
			if((rownum / 464183) > (fileNo - 1)){                    
				fw.close();                    fileNo ++ ;               
				fw = new FileWriter("D:/text"+fileNo +".txt");           
				
			}            
			}            
		fw.close();            
		System.out.println("rownum="+rownum+";fileNo="+fileNo);        
		} catch (FileNotFoundException e) {            
			e.printStackTrace();        } catch (IOException e)
	{            e.printStackTrace(); 
	}    
	}
	
}